Indeno pyrroles

If the heterocyclic base contains several pyridine-type nitrogens select can also be observed. Indeno[l,2-b]quinoxalines, for example, are quaternized at the N-10 atom.110 The alkylation of heterocycles conta one pyrrole-type nitrogen and several pyridine-type nitrogens is appar selective (e.g., indolo[2,3-b]quinoxaline).201 The yields of quaternary however, are extremely low,201 even if phenacyl halides or a-halo ester used.207 Perhaps the resultant quaternary salts are dealkylated.200,207... 

The aromaticity obtained by means of the DE values and their differences in the single pseudoazulene systems are also the result of calculations of the bond orders (Fig. 1). The calculated bond alternations46 57-77-79-82-117118-129 are in line with the heteroaromaticity of the systems. Similar relationships were calculated for azulene.219 The extent of the bond alternation, however, differs from one system to the other (see Fig. 1). In indeno[2.1-f>]-l-benzo-pyran (44a) the bond lengths of the central cyclo[fo]pyran system indicate pronounced bond alternation, and in the opinion of the authors, the systems have little aromatic character.129 Calculations with 1 //-pyrindines (26) and 2//-pyrindines (29) show that 26 is more stable than 29, but both are less aromatic than indole.63 A comparison of SCF calculations for pseudoazulenes 26 and 29 with their aza analogs 68 and 69-73, which contain a pyrrole-type nitrogen, shows only minor perturbations of carbon-carbon bond lengths on replacing a =CH— moiety by =N—.66... 

Bos, M., Jenck, E., Martin, J. R., Moreau, J.-L., Sleight, A. J., Wichmann, J., Widmer, U. Novel agonists of 5HT2C receptors. Synthesis and biological evaluation of substituted 2-(indol-l-yl)-l-methylethylamines and 2-(indeno[l,2-h]pyrrol-l-yl)-l-methylethyl-amines. Improved therapeutics for obsessive compulsive disorder. 7. Med. Chem. 1997,40,2762-2769. 

In general, pyrolysis of monocyclic 1,2,3-triazines 1 leads to acetylenes, nitriles and nitrogen.46, 295 297 300 Heating simple 1,2,3-triazines in a sealed tube led to the isolation of pyridines, pyrimidines, pyrazoles, pyrroles, pyridazine, and indeno[3,2-/>]pyridine, depending on the substituents bound to the 1,2,3-triazine ring and the reaction conditions.46 A mechanism formulated for the formation of these products involves an azete as an intermediate. 

The Ring Name Index is an alphabetical list of the systematic names of all ring systems, e.g. Benzo[4,5]indeno[l,2-c]pyrrole [RF 40064]. The Ring File Number allows access to the Ring Systems File. 

Azizian, J., Karhni, A.R., Kazemizadeh, Z., Mohammadi, A.A., Mohammadizadeh, M.R. 2005. Silica snlfuric acid-catalyzed reaction of 4-hydroxy proUne with llH-indeno[l,2-b] quinoxalin-ll-one and isatin derivatives A novel synthesis of new pyrrole compounds. Synthesis 1095-1097. 

Reaction Procedure (Scheme 2.190) A mixture of 2-allgmylbromobenzene (0.2 mmol), propargylic sulfonamide (0.3 mmol), Pd(PhCN)2Cl2 (10 mol%), DPEPhos (10 mol%) and K2CO3 (0.4 mmol) in toluene (0.5 mL) was stirred at 80 °C. After completion of the reaction as indicated by TLC (usually 10 hours), the residue was purified immediately by flash chromatography on silica gel to provide indeno[l,2-c]pyrrole. 

Alizadeh A, Zarei A, Rezvanian A (2011) A novel and one-pot multicomponent approach to the synthesis of dihyroindeno[l,2-6]pyrroles and indeno[2, l 4,5]pyrrolo[l,2-a]-fused 1,3-diazaheterocycles. Synthesis 2011 497-501... 

Using Pd2(dba)3 instead of Pd(0Ac)2, the intramolecular C2 arylation of a pyrrole unit was accorr5>lished to produce a l //-spiro[fluorene-9,4 -indeno[l,2-fc]p3Trole] derivative in modest yield (eq 29). ... 

An efficient, three-component method for the construction of ll-(lH-pyrrol-l-yl)-llH-indeno-[l,2-li]quinoxalines has been worked out by Azizian et al. [60]. The reaction, catalyzed by montmorillonite KIO (Mont K-10) under MW irradiation, is carried out via condensation of ninhydrin, 1,2-phenylenediamine, and 4-hydroxyproline. The authors propose that an azomethine ylide 42 is formed as the intermediate, which undergoes dehydration (catalyzed by Mont K-10) spontaneously to produce the conjugated azomethine ylide 43. Proton transfers could then give azomethine ylide 44, which in turn furnishes the desired product (Scheme 38). 

J. Azizian, A.R. Karimi, Z. Kazemizadeh, A.A. Mohammadi, M.R. Mohammadizadeh, A synthetic route to ll-(lH-pyrrol-l-yl)-llH-indeno[l,2-i)]quinoxaline derivatives exploiting a three-component coupling strategy under microwave irradiation. Tetrahedron Lett. 46 (2005) 6155-6157. 

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